OGLE-ing the Magellanic System: RR Lyrae Stars in the Bridge

Anna M. Jacyszyn-Dobrzeniecka, P. Mróz, K. Kruszyńska, I. Soszyński, D. Skowron, A. Udalski, M. K. Szymański, P. Iwanek, J. Skowron, P. Pietrukowicz, R. Poleski, S. Kozłowski, K. Ulaczyk, K. Rybicki, M. Wrona

Published 2019-04-16Version 1

We use the extended and updated OGLE Collection of Variable Stars to thoroughly analyze distribution of RR Lyrae stars in the Magellanic Bridge. We use photometric metallicities to derive absolute Wesenheit magnitude and then individual distance of each RR Lyr star. We confirm results from our earlier study showing that RR Lyr stars are present in between the Magellanic Clouds, though their three-dimensional distribution rather resembles two extended overlapping structures than a strict bridge-like connection. The contours do connect in the southern parts of the Bridge, albeit on a too low level to state that there exists an evident connection. To test the sample numerically, we use multi-Gaussian fitting and conclude that there is no additional population or overdensity located in the Bridge. We also try to reproduce results on putative RR Lyr Magellanic Bridge stream by selecting RR Lyr candidates from Gaia Data Release 1. We show that we are not able to obtain the evident connection of the Clouds without many spurious sources in the sample, as the cuts are not able to remove artifacts and not eliminate the evident connection at the same time. Moreover, for the first time we present the Gaia Data Release 2 RR Lyr stars in the Magellanic Bridge area and show that their distribution matches our results.